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Lab 2 - B03 Nutritional Composition of Beer $9.49   Add to cart

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Lab 2 - B03 Nutritional Composition of Beer

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Nutritional Composition of Beer Introduction: The purpose of the experiment was to determine the nutritional composition of beer, specifically the amounts of sugar, protein, and amino acids. This was significant because beer can then positively or negatively contribute to an individual’s diet...

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  • January 30, 2023
  • 16
  • 2022/2023
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Ava Clark

Partner: Emma Kobelsky

B03

Nutritional Composition of Beer


Introduction:

The purpose of the experiment was to determine the nutritional composition of beer,

specifically the amounts of sugar, protein, and amino acids. This was significant because beer

can then positively or negatively contribute to an individual’s diet. The determination of

reducing sugars was completed by a DNS assay, which occurs by one molecule of 3,5-

dinitrosalicylic acid (DNS) reacts with one molecule of reducing sugar under basic conditions

and heat, which was then measured with the spectrophotometer at 540 nm to find glucose

concentration. To find protein concentration in the sample of Kokanee beer the Folin-Lowry

assay was used. It works by complexing two adjacent peptide bonds in a protein with a Cu2+ ion

(Biuret reaction) and then adding Folin-Ciocalteu reagent, which improves sensitivity of protein

detection and oxidizes the metal ion to produce a blue color that was detected with

spectrophotometry at 750 nm. The Ninhydrin assay was used to determine amino acid

concentration due to ninhydrin reacting with deprotonated primary amines, giving an orange-red

colour that was detected at 570 nm with the spectrophotometer [1]. The techniques employed for

this experiment included spectrophotometry, which works by detecting the intensity of light that

passes through the sample (absorbance), providing information on the concentration of the solute

[2]. Based off of the literature, it was hypothesized that the amount of sugars present would be

minimal because they are added in small quantities to balance sourness and bitterness [3], protein

would be present in amounts ranging from 0.15-0.40% [4], and glycine has previously been

found at 0.63 – 0.74 g/mL (0.0083-0.010 mM) [5].

, Ava Clark

Partner: Emma Kobelsky

B03

Nutritional Composition of Beer


Methods:

No changes were made to the online lab manual pp. 2.1-2.6 [1].



Results:



Table 1.0: Concentration of Glucose (mole/mL) and Corresponding Absorbance Readings at

540 nm for the DNS Assay.

Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7
Glucose 0.000 0.200 0.400 0.600 0.800 0.224 0.455
Concentration
(mole/mL)
Absorbance 0.000 0.100 0.253 0.372 0.502 0.143 0.291
at 540 nm


The trend in Table 1.0 shows that as absorbance at 540 nm increases, glucose

concentration (mole/mL) for the standard curve also increase, giving rise to a linear relationship

between absorbance and glucose concentration. Unknown tube 6 falls between tube 2 and tube 3,

while unknown tube 7 falls between tube 3 and tube 4.



Table 2.0: Concentration of Protein (mg/mL) and Corresponding Absorbance Readings at 750

nm for the Folin-Lowry Assay.

Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7

, Ava Clark

Partner: Emma Kobelsky

B03

Nutritional Composition of Beer


Protein 0.000 0.007 0.014 0.027 0.041 0.014 0.038
Concentration
(mg/mL)
Absorbance 0.000 0.091 0.136 0.246 0.354 0.117 0.315
at 750 nm


The trend in Table 2.0 shows that as absorbance at 750 nm increases, protein

concentration (mg/mL) for the standard curve also increase, giving rise to a linear relationship

between absorbance and protein concentration. Unknown tube 6 has the same protein

concentration as tube 2, but a lower absorbance. Unknown tube 7 falls between tube 4 and tube

5.



Table 3.0: Concentration of Glycine (mole/mL) and Corresponding Absorbance Readings at

570 nm for the Ninhydrin Assay.

Standard Curve Unknown
Tube Number 1 2 3 4 5 6
Glycine 0.000 0.005 0.015 0.025 0.013 0.028
Concentration
(mole/mL)
Absorbance 0.000 0.000 0.116 0.304 0.164 0.348
at 570 nm


The trend in Table 3.0 shows that as absorbance at 570 nm increases, glycine

concentration (mole/mL) for the standard curve also increased, giving rise to a linear

relationship between absorbance and glycine concentration. Unknown tube 5 falls between tube

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